A careful reading of the Torah’s account of MatanTorah indicates
that the Jewish people accepted the Torah not once but twice.
First it says:

“Moses came and told the people all of God’s words and all of the
laws. The entire people responded with a single voice, ‘All the
words that God spoke — we will do (Na’aseh).'” (Ex. 24:3)

Immediately afterward, we read:

“Moses wrote down all of God’s words.... He took the book of the
covenant and read it to the people. They responded, ‘All that God
said, we will do and we will understand — Na’asehVeNishma.'”
(Ex. 24:4,7)

These two passages cannot refer to the same event. In the first
account, Moses communicated God’s words orally, while in the
second account he read to the people from seferhabrit, the
written record of God’s word.

This corresponds to the teaching of the Sages that not one
but twoTorahs were given at Mount Sinai — the Oral Law and the
Written Law. The Jewish people first accepted upon themselves the
Oral Torah, and afterward, the Written Torah.

Why Two Torahs?

Why was it necessary for the Torah to be given both orally and in
writing? And why did the people accept the Oral Torah with the
words, “We will do,” but when accepting the Written Torah they
added, “and we will understand"?

There are two aspects to Torah study. The primary goal of Torah
is to know how we should conduct ourselves. This is the function
of the Oral Law — the Mishnah and the Talmud — which discusses in
detail how to apply God’s laws to the diverse situations of life.

The second goal of Torah study is to know the Torah for its own
sake, without practical applications. This goal is particularly
relevant to the Written Torah. Even if we do not fully understand
the words and intent, we still fulfill the mitzvah of Torah study
when we read the Written Torah. As the Sages taught: “One should
first learn superficially, and later analyze [the material]...
even if one does not [initially] understand what one has read”
(Avodah Zarah 19a).

There is no value, however, in studying the Oral Torah if it is
not understood properly. On the contrary, misreading the Oral Law
will lead to errors in Halachic rulings and faulty conduct.

Attaining accurate insight into the practical application of
Torah principles requires a breadth and depth of Torah
scholarship. It is unreasonable to expect the entire people to
reach such a level of erudition. For this reason, the practical
side of Torah was transmitted orally. Only those who labor
diligently in its study, receiving the traditions from the great
scholars of the previous generation, will truly merit this
knowledge. If this part of Torah had been committed to writing,
many unlearned individuals would be falsely confident in
rendering legal decisions, despite not having studied all of the
relevant issues.

One might argue that perhaps the entire Torah should have been
transmitted orally. But then Torah knowledge would be limited to
only a select few. The Written Torah enables all to be exposed to
Torah, on whatever level they are capable of comprehending.

Now we can better understand the Torah’s account of Mount Sinai.
When they first accepted the Oral Law, the people promised,
'Na’aseh.' This aspect of Torah related to the entire people only
in terms of its practical application — “We will do.” It was with
regard to the Written Torah, which is intellectually accessible
to all, that the people added, 'VeNishma' — “and we will
understand.”

First — “We Will Do"

It is natural to want to understand as much as possible and to
act according to our understanding. The spiritual greatness of
the Jewish people at Mount Sinai was their recognition of the
benefit of not committing the Oral Law to writing so that their
actions would best fulfill God’s Will. This is the significance
of their response, “We will do": we accept upon ourselves to
follow the practical teachings of the scholars and teachers of
the Oral Law. Since this acceptance was equally relevant to all,
regardless of intellectual capabilities, the verse emphasizes
that “the entire people responded with a single voice.”

After they had accepted upon themselves to observe the Torah
according to the teachings of the rabbis, Moses then presented
them with the Written Torah. We would have expected that the
people would have shown particular love for the Written Law,
since they could approach this Torah directly. But in an act of
spiritual nobility, the Jewish people demonstrated their desire
to first obey and observe the applied rulings of the Oral Law.
Thus they announced: “We will do,” and only afterward, “we will
understand.”

In summary: the Jewish people received two Torahs at Sinai. Moses
first gave them the Oral Law, so they could fulfill the Torah’s
principal goal — proper conduct in this world. Then Moses
transmitted the Written Law, enabling each individual to access
Torah at his level, and preparing the people to receive the
practical teachings of the Oral Law.